JPH0261082B2 - - Google Patents

Description

[Detailed description of the invention]

"Industrial Application Field" The present invention is used in the microwave region, particularly in the frequency region above the X-band, and is an alumina porcelain composition that exhibits a high no-load Q and a low dielectric constant in these high frequency regions. This is what we are trying to provide. “Prior art” Conventionally, ZrO ₂ −SnO ₂ − was used as a dielectric ceramic material.
TiO ₂ -based BaO-TiO ₂ -based porcelain, porcelain in which part of it has been replaced with other elements, or dielectric porcelain or glass with a positive temperature coefficient of dielectric constant, and TiO ₂ with a negative value. It is known that attempts have been made to control the temperature coefficient by combining materials, but these materials have a high dielectric constant of 30 to 40. On the other hand, as the frequency of use increases, materials with a small dielectric constant are required for ceramics for dielectric resonators from the viewpoint of workability. Alumina porcelain is attracting attention as a material with such a low dielectric constant. The dielectric constant of alumina porcelain is
10, but the temperature coefficient of the resonant frequency was extremely large at -60 ppm/°C. The applicant previously filed Japanese Patent Application No. 59-151589 (Japanese Unexamined Patent Publication No.
61-32306), Al ₂ O ₃ −CaTiO ₃ −
In the SrTiO ₃ ternary composition diagram, the mole fractions are dotted. Al ₂ O ₃ CaTiO ₃ SrTiO ₃ points A 0.99 0.01 0 point B 0.96 0.04 0 point C 0.91 0.04 0.05 point D 0.91 0.01 0.08 Composition within a quadrilateral area formed by sequentially connecting points A, B, C, and D Then, the temperature coefficient of the resonant frequency (hereinafter 〓
f), it takes a negative value with a large absolute value of -60 ppm/℃, has a high no-load Q, and has low dielectric loss at high frequencies, and is rich in thermal conductivity, mechanical strength, and chemical stability. It is produced by alumina sintered body, CaO and TiO ₂ , and the above
An alumina porcelain composition that is excellent as a high-frequency dielectric material in a two-component system made by combining it with a small amount of calcium titanate (CaTiO ₃ ) having a large positive value of f close to +900, and in a three-component system by adding stroium titanate. I proposed about. ``Problems to be Solved by the Invention'' This invention attempts to further improve the no-load Q obtained by the invention of Japanese Patent Application No. 59-151589. "Means for Solving the Problems" The present invention consists of the alumina sintered body of the above-mentioned Japanese Patent Application No. 151589/1982 and calcium titanate in a molar ratio of 96 to 99.5% alumina and 4 to 0.5% calcium titanate.
%, and by containing MgO at a ratio of 1 part by weight or less per 100 parts by weight of the composite of both, the no-load Q can be particularly increased and the comparative voltage can be improved. The aim is to reduce the rate. "Effect" The above MgO increases the no-load Q and lowers the relative dielectric constant. "Example" (1) Synthesis of calcium titanate Calcium carbonate (CaCO ₃ commercial product/reagent special grade)
555g titanium dioxide (TiO ₂ commercial product, reagent grade) 445g water 1500ml and 2kg alumina coccule (purity 99.99%, 20mmφ)
and using 2 polyethylene containers,
Mixing was carried out at 84 RPM for 20 hours, and after drying, 42 meshes were passed through a sieve, transferred to an aluminum crucible with a purity of 99.99, and calcined in an electric furnace at 1300℃ for 1 hour to synthesize CaTiO ₃ . After passing through a sieve, 42 meshes of calcium titanate CaTiO ₃ powder were obtained by re-pulverizing, drying, and passing through a sieve under the same conditions as the mixing performed before calcination. (2) Mixed alumina (commercial product, purity 99.99%, average particle size
To 950 g of 0.5 μ), the above-synthesized calcium titanate was blended as the final product so as to obtain each molar ratio shown in Table 1, and further, to 100 parts by weight of these blends, the amount of MgO shown in the table was added. Add magnesium carbonate (MgCO ₃ commercial product, special grade reagent) and 1000 ml of water to contain 0 to 1.2 parts by weight as shown, and add alumina coccule (purity 99.99).
%・20mmφ) 2Kg into a polyethylene container No. 8, and mixed at 60RPM for 20 hours. Added 30g of a 33% aqueous solution of polyvinyl alcohol as an organic binder to each mixture and mixed again for 3 hours. The slurry is heated to a gas temperature of 180℃ and an atomizer of 100mm.
Granulation was performed by spray drying at φ 7200 RPM. The 40-150μ granule powder granulated by spray drying is sized to 19mm by a 1500Kg/ ^cm2 mold press.
Formed into φ×10.5mmL, 1400~1450 in electric furnace
℃ for 1 hour, then 15mmφ
Polished to x8mmL. The finishing accuracy was 0.1S on both ends and 0.5S on the outer circumference, and the results of measuring the no-load Q and dielectric constant ε of each sample are shown in Table 1.

【table】

[Table] Measurement method
ε Dielectric cylindrical resonator method (resonance frequency 8GHz)
by.
“Effects of the invention” As shown in Table 1, the effects of the invention
Samples Nos. 1 to 5 have a molar ratio of Al ₂ O ₃ /CaTiO ₃ in the range of 99.5/0.5 to 96/4 and contain MgO within 1.0% by weight, and sub Nos. B to H, respectively. All samples have an unloaded Q of over 7000 and a relative dielectric constant of ε13.
It exhibits the following properties and is particularly effective for use in the microwave region, particularly in the frequency region above the X-band.

Claims (1)

[Claims] 1 _{Al2O3 96-99.5} mol%, _CaTiO3 4-0.5 mol%
An alumina porcelain composition containing MgO as a subcomponent in a ratio of 1 part by weight or less to 100 parts by weight of the main component.